This invention relates in general to combined transmission and axle assemblies, commonly referred to as transaxles, and in particular to an improved shift mechanism for such a transaxle.
In many small powered vehicles, such as riding lawn mowers, garden tractors, golf carts, snowmobiles, and the like, a transaxle is used to provide a driving connection between an engine and a pair of driving wheels. The transaxle includes a housing which contains both a transmission, which is adapted to provide a plurality of gear ratios between the input and output thereof, and an axle assembly, including a differential mechanism. The transmission portion of the transaxle typically includes a gear shaft rotatably mounted within the transaxle housing, a plurality of gears rotatably carried on the gear shaft, and a pair of shift keys for selectively connecting one of the gears to the shaft for rotation therewith. The shift keys are located in opposed longitudinal grooves formed in the gear shaft. An annular collar is supported on the gear shaft and is connected to one end of each of the shift keys. Axial movement of the collar causes corresponding axial movement of the shift keys and consequent changing of the gear ratio of the transmission.
To effect axial movement of the collar, a detent plate is provided. The detent plate has a depending boss formed thereon which extends into an annular groove formed in the outer surface of the collar. Thus, movement of the detent plate causes movement of the collar. The detent plate is secured to a rotatable shift shaft. The shift shaft extends perpendicular to the gear shaft upwardly out of the transaxle housing and the body of the vehicle to a location where it can be grasped by an operator of the vehicle and selectively rotated. To change the gear ratio of the transmission mechanism, the operator grasps and rotates the shift shaft. Such rotation causes the detent plate to pivot about the shift shaft, thereby causing axial movement of the collar and the shift keys as described above.
While the shifting mechanism described above has proven to be effective, it has been found to be occasionally inconvenient to have the shift shaft extend upwardly out of the transaxle. In this arrangement, the shift shaft is usually located between the legs of the operator sitting on the vehicle, an area which is difficult to reach or move comfortably. Some attempts have been made to modify the shift shaft so that after it extends upwardly through the transaxle housing, it bends sideways so as to extend through the side of the body of the vehicle, where it is more convenient to reach. Unfortunately, these modified shift shafts are somewhat difficult to manufacture and maintain in proper position because the shafts are relatively long in length and usually have one or more bends formed therein. Thus, it would be desirable to provide an improved side shifting mechanism for a transaxle which is simple and inexpensive in construction.